The present invention relates to a vehicle seat and, more particularly, to a vehicle seat having a mechanism for moving a headrest in a rear-end collision.
When a collision of a vehicle, such as an automobile, occurs from the rear (a so-called rear-end collision), the head of a seated passenger is moved suddenly to the rear by inertia, and the neck may be shocked. Therefore, there has conventionally been known a vehicle seat provided with a configuration for buffering a shock by moving the headrest to the front and supporting the passenger's head at the time of the occurrence of rear-end collision to protect the head, the neck, and the like of the passenger from the shock in a rear-end collision (see, e.g., Japanese Unexamined Patent Application Publication No. 2006-182094 (“the '094 Application”)).
The vehicle seat described in the '094 Application has a configuration in which a plate body is mounted to a seat back frame of a seat back to be movable back and forth, a headrest is mounted in the upper part of the seat back frame to be movable by an upper link, a lower link connected to the plate body is rotatably provided in the lower part of the seat back frame, and the lower link and the upper link are connected to each other by a transmission member, and is configured so that a load sensed by the plate body at the time of rear-end collision is transmitted to the upper link to move the headrest to the front.
For this vehicle seat, the load at the time when the passenger is moved to the rear by rear-end collision is received by a portion near the waist having a rearward displacement larger than that of the back, whereby the rear-end collision can be sensed with certainty. Also, by the configuration in which the load received by the plate body is transmitted to the upper link via the transmission member, the load can be transmitted to the upper link with high transmission efficiency, so that the operation for moving the headrest to the front becomes reliable.
FIG. 12 is a perspective view of a seat back frame 100 for the above-described conventional vehicle seat, and FIG. 13 is a sectional view taken along the line Z-Z of FIG. 12, showing a portion in which an airbag module 110 for a side airbag is mounted to a side frame 101 of the seat back frame 100. In the vehicle seat described in the '094 Application, a transmission member 107 connecting an upper link 105 to a lower link 106 is mounted to cover a part of the inside of the side frame 101 of the seat back frame 100. Therefore, when a member such as the airbag module 110 or an armrest is attached to the outside of the side frame 101, the attachment from the inside of the side frame 101 has been difficult to attach.
Specifically, as shown in FIG. 13, the airbag module 110 is attached to the side frame 101 via fasteners 103 such as bolts and nuts. Reference numeral 112 denotes an inflator in the airbag module 110. Since the transmission member 107 connecting the upper link 105 to the lower link 106 is located at a position overlapping with the position of a mounting hole 102 formed in the side frame 101 to allow the fastener 103 to pass through, a tool for attaching the airbag module 110 or the like is difficult to access because of hindrance placed by the transmission member 107, and therefore the attaching work is difficult to do.
Also, in the conventional vehicle seat having a configuration in which the headrest is moved to the front at that time of the occurrence of rear-end collision to support the passenger's head, the number of parts for forming the configuration is large. Therefore, it is desired to decrease the number of parts and to reduce the weight of seat.